Bidirectional ramped disposable torque limiting device

ABSTRACT

A bidirectional torque limiting driver with a handle, internal wall, movable head and a tool mounted thereon, with flexible torque limiting flex ramp(s) formed on said internal wall, whereby said ramps move under sufficient force to impart a predetermined torque to a tip is disclosed.

RELATED APPLICATIONS

The present application is a U.S. National Stage of InternationalApplication No. PCT/US2012/066090, filed Nov. 20, 2012, which claims thebenefit of and priority to U.S. Provisional Application No. 61/610,405,filed Mar. 13, 2012, the entire disclosures of each of which areincorporated herein by reference in their entireties.

BACKGROUND

1. Field

This disclosure relates to a medical use driver tool and, in particular,to a bidirectional torque-limiting driver that disengages at apredefined torque limit, which provides for a predetermined number ofuses.

2. General Background

Torque-limiting drivers are widely used throughout the medical industry.These torque-limiting drivers have a factory pre-set torque to ensurethe accuracy and toughness required to meet a demanding surgicalenvironment.

The medical industry has made use of both reusable and disposabletorque-limiting drivers. In a surgical context, there is little room forerror and these drivers must impart a precise amount of torque.

Reusable drivers require constant recalibration to ensure that thedriver is imparting the precise amount of torque. Recalibration is acumbersome task but must be done routinely.

Disposable drivers are an easy to use and reliable alternative to thereusable drivers. Typically, each implant, for example, is packaged witha disposable driver designed to the implant's specifications. Once thedriver has been used, it can be discarded. Thus, a surgeon can havecomplete confidence that the disposable driver, packaged with animplant, will impart the precise amount of torque.

DESCRIPTION

Torque is a measure of how much force acting on an object causes thatobject to rotate. In the case of a driver and a fastener, thismeasurement can be calculated mathematically in terms of the crossproduct of specific vectors:T=r×F

Where r is the vector representing the distance and direction from anaxis of a fastener to a point where the force is applied and F is theforce vector acting on the driver.

Torque has dimensions of force times distance and the SI unit of torqueis the Newton meter (Nm). The joule, which is the SI unit for energy orwork, is also defined as an Nm, but this unit is not used for torque.Since energy can be thought of as the result of force times distance,energy is always a scalar whereas torque is force cross-distance and sois a vector-valued quantity. Other non-SI units of torque includepound-force-feet, foot-pounds-force, ounce-force-inches,meter-kilograms-force, inch-ounces or inch pounds.

A simple torque limiting driver that will provide a predetermined numbercycles at a nominal torque limit is disclosed.

In some exemplary implementations, the actuation to be in either theclockwise direction or the counterclockwise direction each having atorque setting of 15.0+3.0/−2.0 oz-in under no axial load. Maximumtorque must remain under 20.0 oz-in under a measured axial load up to5.0 lbs.

In some exemplary implementations, the actuation to be in either theclockwise direction or the counterclockwise direction, each having atorque setting of 15.0+3.0/−2.0 oz-in under no axial load. Maximumtorque must remain under 20.0 oz-in under a measured axial load up to5.0 lbs and there is about 15.0 degrees of minimum free play.

In some exemplary implementations, movable torque limiting flex ramps(TLFR) are formed on a wall bisecting said handle and locking stops areassociated with movable nose cone.

In some exemplary implementations, movable torque limiting flex ramps(TLFR) are formed on a wall bisecting said handle and force headsassociated with movable nose cone provide for actuation. Such actuationbeing the result of said TLFR acting as a living hinge, which moves inresponse to the force heads passing thereover at a predetermined force.TLFRs can flex in response to the passing of the force head(s)thereover.

In some instances, a nose cone may be molded in a plastic that hasbetter lubricity properties than said handle. Driver will have about15.0-degree minimum free play. Torque limiting driver is disposed ofafter one torque actuation.

In some exemplary implementations, there is disclosed a bidirectionaltorque limiting device comprising: a hollow body with and open proximalend and open distal end forming a handle; an internal wall bisectingsaid hollow body into a first and a second section on one side having atleast one movable torque limiting flex ramp; a channel formed throughsaid internal wall fluidly connecting said first and said secondsections; a head surrounded by an annular wall which fits movably intosaid hollow body said head having a front side with a nose extendedtherefrom which has a tool mounted therein; said head having a backsidewhich fits over said ramp further comprising; at least one force head; apeg extended therefrom having a catch; a plug with an extended latch ofa size and shape to fit through said channel which mates with said peg'scatch holding said head to said internal wall; whereby when rotated ineither a forward or reverse direction the at least one force head willpass over said ramp and upon the application of sufficient torque allowpassage of said force head, thereby biasing the device to apredetermined torque per ramp over movement.

In some exemplary implementations, there is disclosed a bidirectionaltorque limiting device comprising a hollow body with and open proximalend and open distal end forming a handle; an internal wall bisectingsaid hollow body into a first and a second section on one side having aat least one torque limiting flex ramp with a leading edge; a channelformed through said internal wall fluidly connecting said first and saidsecond sections; a head surrounded by an annular wall which fits movablyinto said hollow body said head having a front side with a nose extendedtherefrom which has a tool mounted therein; said head having a backsidewhich fits over said ramp further comprising; at least one force head; apeg extended therefrom having a catch; a plug with an extended latch ofa size and shape to fit through said channel and mates with said peg'scatch holding said head to said internal wall; and, whereby when rotatedthe at least one force head must apply a preselected amount of force topass over said ramp, said ramp moving downward and allowing passage.

In some instances, a tool affixed to the nose of the bidirectionaldevice is rotated by an amount of force corresponding to the force saidstop is applying to said at least one ramp. In some instances, said rampis a natural or living hinge, fixed to said internal wall having abridge raised above two shoulders, each shoulder connected to saidinternal wall and said bridge will move downward under sufficient forceor load when said force head passes thereover.

In some exemplary implementations, a method of applying a torquelimiting actuation to a tip is disclosed whereby a user engages the tipof a driver to a fastener; applying the predetermined torque to depressor otherwise move said ramp downward via a rotational handle; tighteningsaid fastener to the torque limit.

DRAWINGS

The above-mentioned features of the present disclosure will become moreapparent with reference to the following description taken inconjunction with the accompanying drawings wherein like referencenumerals denote like elements and in which:

FIG. 1 shows a front perspective component view of some aspects of anexemplary implementation of a single use torque limiting device;

FIG. 2 shows a front perspective view of some aspects of an exemplaryimplementation of a single use torque limiting device;

FIG. 3A shows a back view of the head component of FIGS. 1 and 2.

FIG. 3B shows a view of the front section of the handle component ofFIGS. 1 and 2.

FIG. 3C shows a close-up view of aspects of at least one exemplaryimplementation of part of the internal wall and ramps for abidirectional torque limiting device.

FIG. 4A shows a cut-away side view of some aspects of an exemplarilyimplementation of a single use torque limiting device.

FIG. 4B shows a cut-away of the handle showing the ramps of FIG. 4A.

While the specification concludes with claims defining the features ofthe present disclosure that are regarded as novel, it is believed thatthe present disclosure's teachings will be better understood from aconsideration of the following description in conjunction with theappendices, figures, in which like reference numerals are carriedforward. All descriptions and callouts in the Figures are herebyincorporated by this reference as if fully set forth herein.

FURTHER DESCRIPTION

Referring to FIGS. 1-4B: In FIG. 1 there is shown an assembly view of asingle use torque-limiting driver 100. The torque-limiting driver 100has a generally hollow body 110 forming a handle with an open proximalend 115, an open distal end 120, and an internal circular wall 122bisecting the handle into a first and a second section, which are shownas a front section 125 and a back section 220. Flexible ramps are formedon said wall. The illustration of said handle as a cylindrical device isnot a limitation; said device may be other curved or geometric shapessuch as ellipsoid, conical, square, polygonal and the like. Those ofordinary skill in the art will recognize that such design choices areall within the scope of this disclosure.

A circular cap 130 with a backside 132, a front side 134, and an annularwall 135 which extends from said front side 134, and of a size and shapeto form a latch with said open proximal end 115 is shown in FIGS. 1-4.

A tool 140 with a tip 145 at its distal end and a fixed mount 150 at itsproximal end is affixed at its proximal end into a mounting guide 160located in a nose 165 extending from the front side of a head 170component, the head acts as a support for the tool. The tip may be adrive for tightening fasteners or a cutting instrument. To effectivelyapply torque via the tip, the tip must be engaged. In some instances,said engagement will be with a fastener. In other instances, saidengagement may be with material to be cut or resected. The headcomponent is a movable element with an annular wall 175. The annularwall defines a diameter around the circular head that fits within saidopen distal end 120.

Although not fully visible in FIGS. 1 and 2, said head component 170 hasa catch formed on its backside wherein a head plug 180 provides a latch185 that fits through a plug channel through internal circular wall 122.In FIGS. 3 and 4, the plug channel 188 is shown.

The back side 177 of the head 170 is surrounded by an annular wall 175.The plug catch 178 is shown formed center aligned in a cylindrical peg179 thereby providing a point whereby said head plug can movably attachsaid head to the internal circular wall 122 whereon the head may berotated in furtherance of the disclosure. To effectuate a torque limitedrotation as well as fixed reverse rotations (without torque limiting) acooperative system is disclosed whereby a head piece attached to thebisecting internal circular wall via a head plug interacts withoperational features formed on said internal wall 122.

In FIGS. 3A and 3B, force heads 202 are shown extending from backside177 of the head 170 component, which also acts as a support for theforce heads. Said force heads 202, may have two opposing angled faces203A and 203B formed on each side. Said angled faces are optional andnot essential. During a rotation in a forward or backwards direction,the angled faces 203A and 203B move over torque limiting flex ramps(TLFR) 210 formed in said internal circular wall and do not catch.Rather, at least one force head will eventually encounter a torquelimiting flex ramp (TLFR) 210. Said TLFR is raised from said internalwall 122 and limits the movement of the force head thereover—unless oruntil—sufficient force is applied during rotation to move the force headover the TLFR and overcome the TLFR's resistance to a downward movement,which allows passage of said force head.

A TLFR 210 is formed to require a predetermined amount of force, appliedthereto via said force heads 202, to overcome the TLFR's impediment torotation of the force head over said TLFR, which is movable under apredetermined force. When adequate force is applied by the force head202 (or heads) the TLFR (or TLFRs) move in a direction downward from theforce head (towards the internal wall 122) and generally axial in thedevice.

In some instances, a single force head 202 may be used. In otherinstances, multiple force heads may be used. In some instances, a singleTLFR may be utilized. In some instances, the single TLFR is provided andit will encounter multiple force heads 202, each force head 202 reachingthe TLFR as the tool 140 is rotated. In some instances, multiple TLFRsare provided. In a multiple TLFR configuration, a single force head 202may be utilized. Said single force head must overcome the necessaryresistance to force to pass over said TLFR during a partial rotation.

In a some multiple TLFR configurations, multiple force heads 202 areutilized. At least two of said multiple force heads may be oriented toeach pass over a different TLFR during a partial rotation of the tool140. In some instances, each of the multiple stops may be oriented topass over a different TLFR during a partial rotation of the tool 140.

FIGS. 3C and 4B show partial blown up views of aspects of componentscomprising said force heads 202 and said TLFR 210. In some exemplaryimplementations, the TLFR 210 is a generally elongated member separatedfrom said internal wall 122 by flex channels 212 which are guides orcutouts in the internal wall along the side edge of said TLFR. A TFLRmay be thought of as a flexible bridge that has a first at rest positionwhich is extended above the internal wall 122 and a second range ofpositions, when force is applied to the TFLR by force head, which movesthe TLFR downward nearer to the internal wall. A TLFR is a two shoulderramp fixture with a first shoulder 215 and a second shoulder 217; theshoulders meeting at a bridge 219. The shoulders each form a leadingedge remote from the bridge. The TLFRs have a side edge 221 with athickness. The TLFR bridge 219, when at rest, is above said internalwall 122 into the front section 120. At a first end 223 the TLFR isaffixed to said internal wall 122 and at a second end 224, said TLFR isalso affixed to said internal wall. In some instances, said flexchannels 212 may extend beyond the point of affixation of said first andsecond ends to said internal wall. A control region 230 of the TLFRbelow the bridge 219 may be non-homogeneous in width or thickness fromthe rest of the TLFR to facilitate controlled movement of the TLFRcorresponding to desired torque limits in response to force beingapplied. A second control region 231 at the connection of the firstshoulder 215 with the internal wall 122 may be non-homogeneous in widthor thickness from the rest of the TLFR to facilitate controlled movementof the TLFR corresponding to desired torque limits in response to forcebeing applied. A third control region 232 at the connection of thesecond end 217 with the internal wall 122 may non-homogeneous in widthor thickness from the rest of the TLFR (which includes regions ofnon-homogeneity) to facilitate controlled movement of the TLFRcorresponding to desired torque limits in response to force beingapplied. Accordingly, a predefined amount of torque to flex the TLFR inresponse to movement of the force heads over the TLFR. The one or morecontrol regions which may be non-homogeneous with the TLFR may be addedto further set, or control, the torque limit of the TLFR. In other wordsto displace the TLFR the force heads must apply a predetermine amount oftorque and a fixed tool tightening a fixture would tighten to thedetermined limit and then pass over the TLFR.

Those of ordinary skill in the art will recognize that several variablesand design choices are involved in preselecting what amount of forcemust be applied to pass one or more stops over one or more TLFRs andachieve a nominal torque limit and that such variables and designchoices are within the scope of this disclosure. Some such variables anddesign choices include but are not limited to the angle of the TLFRrelative to the internal wall 122 the thickness of the TLFR. Alsoimpacting the force requirements will be the lubricity of the materials,the hardness or softness of the materials, the memory of the materials,tensile strength, flexural strength, coefficient of friction, and thestiffness of the materials. A non-exclusive list of materials includepolyetherimide (Ultem) material for all plastic components,polycarbonate (Lexan) material for plastic components, aPolyoxymethylene (Delrin) material for plastic components, and ABS(Acrylonitrile butadiene styrene) for plastic components. Other factorsimpacting force include how many force heads are passing over how manyTLFRs at the same time. These variables are adjustable to meet aparticular torque requirement.

Those of ordinary skill in the art will recognize that said force headsneed not have angled faces to function; while it is preferred to achievesmooth operation and angled faces provide a larger surface to push oversaid TLFR.

FIG. 4A illustrates a cutaway assembled view of a bidirectional torquelimiting. Head plug 180 via its extended latch 185 fits through the plugchannel 188 of the internal circular wall 122 and mates with, to be heldin, the plug catch 178 of said head. In this view, angled faces 203A and203B are not visible. Behind the internal circular wall 122 is the backsection 220 wherein fits the cap 130.

While the method and apparatus have been described in terms of what arepresently considered to be the most practical and preferredimplementations, it is to be understood that the disclosure need not belimited to the disclosed implementations. It is intended to covervarious modifications and similar arrangements included within thespirit and scope of the claims, the scope of which should be accordedthe broadest interpretation so as to encompass all such modificationsand similar structures. The present disclosure includes any and allimplementations of the following claims.

It should also be understood that a variety of changes may be madewithout departing from the essence of the disclosure. Such changes arealso implicitly included in the description. They still fall within thescope of this disclosure. It should be understood that this disclosureis intended to yield a patent covering numerous aspects of thedisclosure both independently and as an overall system and in bothmethod and apparatus modes.

Further, each of the various elements of the disclosure and claims mayalso be achieved in a variety of manners. This disclosure should beunderstood to encompass each such variation, be it a variation of animplementation of any apparatus implementation, a method or processimplementation, or even merely a variation of any element of these.

Particularly, it should be understood that as the disclosure relates toelements of the disclosure, the words for each element may be expressedby equivalent apparatus terms or method terms—even if only the functionor result is the same.

Such equivalent, broader, or even more generic terms should beconsidered to be encompassed in the description of each element oraction. Such terms can be substituted where desired to make explicit theimplicitly broad coverage to which this disclosure is entitled.

It should be understood that all actions may be expressed as a means fortaking that action or as an element which causes that action.

Similarly, each physical element disclosed should be understood toencompass a disclosure of the action which that physical elementfacilitates.

Any patents, publications, or other references mentioned in thisapplication for patent are hereby incorporated by reference. Inaddition, as to each term used it should be understood that unless itsutilization in this application is inconsistent with suchinterpretation, common dictionary definitions should be understood asincorporated for each term and all definitions, alternative terms, andsynonyms such as contained in at least one of a standard technicaldictionary recognized by artisans and the Random House Webster'sUnabridged Dictionary, latest edition are hereby incorporated byreference.

Finally, all referenced listed in the Information Disclosure Statementor other information statement filed with the application are herebyappended and hereby incorporated by reference; however, as to each ofthe above, to the extent that such information or statementsincorporated by reference might be considered inconsistent with thepatenting of this/these disclosure(s), such statements are expressly notto be considered as made by the applicant(s).

In this regard it should be understood that for practical reasons and soas to avoid adding potentially hundreds of claims, the applicant haspresented claims with initial dependencies only.

Support should be understood to exist to the degree required under newmatter laws—including but not limited to United States Patent Law 35 USC132 or other such laws—to permit the addition of any of the variousdependencies or other elements presented under one independent claim orconcept as dependencies or elements under any other independent claim orconcept.

To the extent that insubstantial substitutes are made, to the extentthat the applicant did not in fact draft any claim so as to literallyencompass any particular implementation, and to the extent otherwiseapplicable, the applicant should not be understood to have in any wayintended to or actually relinquished such coverage as the applicantsimply may not have been able to anticipate all eventualities; oneskilled in the art, should not be reasonably expected to have drafted aclaim that would have literally encompassed such alternativeimplementations.

Further, the use of the transitional phrase “comprising” is used tomaintain the “open-end” claims herein, according to traditional claiminterpretation. Thus, unless the context requires otherwise, it shouldbe understood that the term “compromise” or variations such as“comprises” or “comprising”, are intended to imply the inclusion of astated element or step or group of elements or steps but not theexclusion of any other element or step or group of elements or steps.

Such terms should be interpreted in their most expansive forms so as toafford the applicant the broadest coverage legally permissible.

The invention claimed is:
 1. A bidirectional torque limiting devicecomprising: a hollow body (110) with and open proximal end (115) andopen distal end (120) forming a handle; the hollow body including: aninternal circular wall (122) separating the hollow body into acylindrical front section (120) and a back section (220); at least onegenerally elongated torque limiting flex ramp (210) integrally formed ona first side of the internal circular wall; the elongated torquelimiting flex ramp having a first ramped projection connected to theinternal circular wall via first living hinge and a second rampedprojection connected to the internal circular wall via a second livinghinge, both at an incline relative to the internal circular wall andoriented to intersect at a raised peak bridging the two ramped surfaces;the raised peak spaced outward from the first side of the internalcircular wall and comprising a third living hinge; a cavity formed in asecond side the internal circular wall opposite the at least onegenerally elongated torque limiting flex ramp, the cavity generallysized to match both the ramped projections and the three living hingesof the at least one generally elongated torque limiting flex ramp; aplug channel (188) formed through the internal wall fluidly connectingthe cylindrical front and the back sections; a tool head (170) having afront side with a nose (165) extended therefrom which has a tool (140)mounted therein; the tool head having an annular back side surfacelocated between an outermost annular wall sized to movably fit insidethe cylindrical front section of the hollow body and an innermostannular peg wall sized to fit inside the plug channel hole, theinnermost annular peg having a catch feature formed thereon, the annularback side surface containing at least one bump stop (202) protrudingtherefrom; a head plug having a base sized to fit inside the backsection of the hollow body but sized to be larger than the plug channelhole, the head plug having an extended latch protruding from the basethat is sized and shaped to fit through the plug channel hole and fastento the catch feature on the innermost annular peg to secure theoutermost annular wall of the tool head to the first side of theinternal circular wall and the base of the head plug to the second sideof the internal circular wall; whereby when the handle is twistedrelative to the tool, the at least one generally elongated torquelimiting flex ramp on the hollow body will rotate toward the at leastone bump stop on the tool head to an engagement point where the bumpstop contacts the at least one generally elongated torque limiting flexramp, at the engagement point additionally twisting of the handle willresult in a twisting of the tool with a torque limited at level wherethe at least one bump stop deflects the first and second ramp portionsinto the cavity allowing the bump stop to rotate past the at least onegenerally elongated torque limiting flex ramp.
 2. The device of claim 1wherein when rotated, the at least one force head must apply apreselected amount of force to pass over said flex ramp by forcing theflex ramp downward and allowing passage of said force head.
 3. Thedevice of claim 1, wherein a tool affixed to the nose is rotated by anamount of force corresponding to the force said force head is applyingto said at least one flex ramp.
 4. The device of claim 1 wherein saidraised peak is raised above two shoulders (217 and 215), each shoulderconnected to said internal wall (122).
 5. The device of claim 1 whereinsaid flex ramp is connected to the internal wall at the first and secondends (223 and 224).
 6. The device of claim 4 further comprising flexchannels (212) cutouts in the internal wall along the side edge (221) ofsaid ramp.
 7. The device of claim 4 further comprising one or morecontrol regions (230, 231, and 232) formed as part of the flex ramp. 8.The device of claim 1 further comprising one or more control regionsformed as part of the flex ramp.
 9. The device of claim 7 wherein theone or more control regions are located below the raised peak, at theconnection of the first shoulder (215) with the internal wall and at theconnection of the second shoulder (217) with the internal wall.
 10. Thedevice of claim 8 wherein the one or more control regions are locatedbelow the raised peak, at the connection of a first shoulder (215) withthe internal wall and at the connection of a second shoulder (217) withthe internal wall.
 11. The device of claim 9, wherein the one or morecontrol regions are nonhomogeneous in one of width or thickness from theTLFR, whereby predefined amounts of torque are required to flex the TLFRin response to movement of the force heads over the TLFR.
 12. The deviceof claim 10, wherein the one or more control regions are nonhomogeneousin one of width or thickness from the TLFR, whereby predefined amountsof torque are required to flex the TLFR in response to movement of theforce heads over the TLFR.
 13. A bidirectional torque limiting devicecomprising: a hollow body (110) forming a handle; an internal wall (122)separating the hollow body into a cylindrical first section and a secondsection; integrally formed on one side of said wall an elongated torquelimiting flex ramp having a first ramped projection connected to theinternal circular wall via first living hinge and a second rampedprojection connected to the internal circular wall via a second livinghinge, both at an incline relative to the internal circular wall andoriented to intersect at a raised peak bridging the two ramped surfaces;a channel formed through said internal wall fluidly connecting saidfirst and said second sections; a tool head surrounded by an annularwall which fits movably into said hollow body, said tool head having afront side with a nose extended therefrom which has a tool mountedtherein; the tool head having an annular back side surface locatedbetween an outermost annular wall sized to movably fit inside thecylindrical front section of the hollow body and an innermost annularpeg wall sized to fit inside the plug channel hole, the innermostannular peg having a catch feature formed thereon, the annular back sidesurface containing at least one bump stop protruding therefrom; and,whereby, when the handle is twisted relative to the tool head, the atleast one generally elongated torque limiting flex ramp on the hollowbody will rotate toward the at least one bump stop on the tool head toan engagement point where the bump stop contacts the at least onegenerally elongated torque limiting flex ramp, at the engagement pointadditionally twisting of the handle will result in a twisting of thetool with a torque limited at a level whereby the at least one bump stopdeflects the first and second ramp portions into the cavity allowing thebump stop to rotate past the at least one generally elongated torquelimiting flex ramp.
 14. The device of claim 13, wherein a tool affixedto the nose is rotated by an amount of force corresponding to the forcesaid force head is applying to said at least one flex ramp.
 15. Thedevice of claim 13, wherein said flex ramp is connected to the internalwall at the first and second ends (223 and 224).
 16. The device of claim13 further comprising one or more control regions formed as part of theflex ramp.
 17. The device of claim 16 wherein the control regions arelocated below the raised peak, at the connection of a first shoulder(215) with the internal wall and at the connection of a second shoulder(217) with the internal wall.
 18. A method of setting a bidirectionaltorque limit, the method comprising: forming one or more living hingeflex ramps (210) integrally in an internal circular wall, each flex rampaffixed at one end to the wall (122) and a first ramped projectionconnected to the internal circular wall via first living hinge and asecond ramped projection connected to the internal circular wall via asecond living hinge, both at an incline relative to the internalcircular wall and oriented to intersect at a raised peak bridging thetwo ramped surfaces; movably affixing a support (170) having one or moreforce head (202) thereon adjacent to said flex ramps; attaching a tool(140) to said support (170); and, whereby when the handle is twistedrelative to the tool head, the at least one generally elongated torquelimiting flex ramp on the hollow body will rotate toward the at leastone bump stop on the tool head to an engagement point where the bumpstop contacts the at least one generally elongated torque limiting flexramp, at the engagement point additionally twisting of the handle willresult in a twisting of the tool with a torque limited at a levelwhereby the at least one bump stop applies a predetermined amount offorce to deflect the first and second ramp portions into the cavityallowing the bump stop to rotate past the at least one generallyelongated torque limiting flex ramp thereby setting a torque limit thetool must overcome to move.